Hi! I know I'm a new member, but I thought I'd have a look at your SCP :)
Overall, the idea seems pretty original to me, as I've yet to see an SCP which (effectively) can control fire.
there were four things that I noticed, which can be fixed VERY easily :)
though these scars are much smaller and better healed
The "better healed" part of this sentence should be re-worded, as ( I may be wrong ) but I believe it is incorrect grammar :) Try: though these scars are much smaller and have healed more effectively.
Swap the blacked out region so that it covers either the whole of the year, or part of it, instead of the month and date.
As mentioned before, SCP-XXXX is capable of creating and manipulating fire.
Get rid of "As mentioned before". The SCP foundation worker will not need reminding that the same concept was stated earlier in the text.
Appropriate fire proof clothing must be provided for tests.
This may be just me, but make it obvious that the fire proof clothing is for the SCP. (As I said, it may be just me) but at first I thought it meant the personnel carrying out the test were required to wear the fireproof clothing. At which point I was going to point it out that you'd mentioned it twice. But then I read it again.
I REALLY like the idea of this SCP :)
I hope this helps :)